Fox TV hit American Idol, which has thrived despite past scandals, faces new scrutiny this week as rival network ABC presents claims judge Paula Abdul had an affair with a contestant on US television's most-watched show.

In an interview airing on Wednesday on ABC's Primetime Live, former Idol finalist Corey Clark said Abdul coached him privately and gave him money for expensive clothes before he was kicked off the show during its second season for concealing a prior arrest record.

The 24-year-old Kansas native told ABC News that Abdul even "got my haircut for me."

"So she was like, 'You got to have better song choices, and I want to help you do that. I want to look after you like -- like I'm your mom,"' Clark quoted Abdul, 42, as telling him in excerpts of his interview released by ABC on Tuesday.

"And then she was like, 'Well, more like your sister.' And I was like, 'OK, cool, cool, cool," Clark said. "And then she was like, 'Well, maybe more like your special friend."'

According to ABC, Clark claimed Abdul initiated a relationship that began as platonic but turned sexual. ABC also said Clark furnished an answering-machine message from Abdul imploring Clark not to talk about her to the media.

Efforts to reach Abdul's representatives on Tuesday night were unsuccessful. Abdul issued a statement last week calling Clark "an admitted liar and opportunist who engages in unlawful activities."

People familiar with the situation said Abdul's lawyer, Martin Singer, sent a letter to ABC threatening the Walt Disney Co-owned network with legal action. Idol host Ryan Seacrest has also joined Abdul's fellow judges -- Simon Cowell and Randy Jackson -- in rallying to her defense.

Abdul, a former Los Angeles Lakers cheerleader, gained fame in the late 1980s as a pop singer.

News Corp-owned Fox and Idol producers issued a statement saying they would "look into any evidence of improper conduct that we receive." But they urged the public to "examine Mr Clark's motives, given his apparent desire to exploit his prior involvement with American Idol for profit and publicity."

Clark was kicked off American Idol in 2003 for failing to disclose he faced criminal charges of battery and resisting arrest stemming from a fight with his sister. He pleaded no contest to obstructing the legal process.

He resurfaced last week in published stories reporting he was shopping a tell-all book proposal.

American Idol, now in its fourth season, ranks as the most-watched show in US prime time, averaging nearly 28 million viewers for its Tuesday night broadcast. The show has endured a string of scandals, with several contestants ejected from the series because of checkered pasts.